1. Cloud Occurrence at Arctic Atmospheric Observatories Matthew Shupe, Taneil Uttal, Daniel Wolfe, David Welsh AMS Polar Meteorology and Oceanography 2007 Special Thanks for Ny’Alesund MPL Data: Masataka Shiobara, James Campbell

2. Arctic Cloud Stations Barrow SHEBA Eureka Alert Ny’Alesund Tiksi RadarLidar An Example Station Summit

3. SiteInstrumentsDates SHEBA, Arctic OceanRadar, lidar, ceilometer 1997-1998 Barrow, USARadar, lidar, ceilometer 1998 – Present Ny’Alesund, NorwayLidar2002 – Present Eureka, CanadaRadar, lidar2005 – Present Alert, CanadaCeilometer? Tiksi, RussiaNone yetNot yet Summit, GreenlandNone yetNot yet Observatories

4. Data Processing Considerations Use a combination of cloud radar and lidar, depending on station “Cloud fraction” is from the perspective of vertically- pointing, surface-based instruments All but SHEBA must be considered preliminary in nature, more detailed multi-instrument analyses will follow

5. Very cloudy in general at all stations (~75% total) Summer/Fall maximum? Total Cloud Fraction Radar Lidar Surface observations

6. Vertical Distribution Bimodal Dist’n in Vertical Lots of Low-level Clouds Radar Lidar

7. Annual and Vertical Distribution

8. Instruments: radar, lidar, microwave radiometer, radiosonde. Manually classified. Automated system has been developed but not yet applied to all observations at all sites. 1 year of data at SHEBA and 7 years at Barrow. Cloud Type Classification

9. Annual Cycles of Cloud Type Mixed-phase clouds: Maxima in transition seasons. Similar trends and magnitudes between SHEBA and Barrow

10. Liquid is present throughout the year more than half of the time! Occurrence of Cloud Liquid

11. Remarkable similarities Slightly different balance at surface. Vertical Distributions of Cloud Type

12. Annual & Vertical Dist’n of Type

13. High annual fraction: ~75% Remarkable similarities in vertical. Similar dist’n of phase for W. Arctic sites. Liquid is frequent (and important!) Radar-lidar combination at all sites. Classification work at all sites using new algorithm. More detailed analysis of boundaries Conclusions Future Work Thank You.